This invention relates to a sheet for transporting a seated rider over snow, ice and the like.
There are many pieces of equipment which can be used to assist people to slide over slippery surfaces such as snow and ice. Examples of such equipment include slats which can be placed on the feet (skis), sheets of wood, metal or plastic which can be laid or sat upon (toboggan), and frames having two or more runners or skis mounted thereon (sled). In most sled or sledge designs, it is intended for the user to place his legs and feet inside the perimeter of the device. Two other commonly used recreational sliding devices include rubber inner tubes or like-shaped inflatable devises made of plastic and large dish like items made of metal or plastic. Unlike the intended use of most other sled designs, the user of a dish or inner-tube often rides with his legs and feet hanging outside its perimeter. Unfortunately, in these later examples, there is little, if any, steering control or comfort for the user. Because the user can easily tip over and because the smooth-bottomed tube or dish has no rotational control, injury can easily occur. Furthermore, the top surface of a dish is hard and smooth making it difficult for a rider to maintain contact with the surface when the dish is in use. Also, there is little comfort to the user of a dish having a slick surface. Further still, this type of sled usually lacks a handle for the user to grip. Even if there is a handle, the lack of steering control tends to neutralize the advantage of the handle.
One sled design intended to resolve certain of the problems associated with prior art sleds is that described by Schmatz (German patent 2,246,164); however, the Schmatz sled has certain problems that are inherent in its design. One such problem, for example, results from its cushion design, as specifically stated by Schmatz, which only develops its functional shape as a sled at the moment the user sits upon the device. There are numerous other problems with the Schmatz sled in addition to those associated with the cushion containing the foamed plastic feature. For instance, the requirement that the foamed plastic be welded between two molded plastic shapes eliminates the possibility of using certain injection molding techniques to economically manufacture the sled, and to thereby lower the cost of manufacture. Additionally, because of the excessive thickness and the lack of rigidity created by the cushion and foam filling, the steering and control of the sled is made difficult.
Another example of a prior art prior art sled includes a toboggan-like sled consisting of a thin mat of plastic which a rider kneels upon or sits upon with his legs outstretched. Often, a toboggan-like sled has built-in handles with which a driver lifts the front part of the mat to permit sliding, but they generally have no runners to permit steering.
The patent literature describes modified dish-like sleds having tub-like shapes and shapes and runners and channels to aid in directional control (see, for example, U.S. Pat. Nos. 4,603,870 and 4,666,171). They are designed to carry a person in a kneeling, sitting or prone position. All body parts are retained within or immediately above the sled structure. As such, they are relatively heavy devises which are difficult to drag up a slope and are stiff and bulky, thus being inconvenient for storage in a garage or automobile. Some sliding vehicles attempt to solve the problem of bulkiness by being articulated or foldable platforms (U.S. Pat. Nos. 4,170,367 and 4,609,201). Such designs, have the disadvantage of being subject to damage or accelerated wear at the relatively fragile folding areas. Moreover, folding alone does not address the weight problem of larger sleds designed to hold the rider in a kneeling or prone position. Furthermore, the use of folding means result in not permitting the use of flexible type devices that allow the sled to form with the contours of a human rider.
Known arrangements of hand grips on sleds, if present, vary from simple knotted ropes or loops of rope fixed to the sled, to depressions, lips or holes stamped or molded into the body of the sled. Many of these hand grips elements have the disadvantage of not being well placed on the sled. They create strain and discomfort and, in some instances, can cause injury when being used. It is desirable, therefore, for a sliding vehicle to have anthropomorphically designed had grips.
Many sliding platforms also have upper surfaces that are smooth and slippery thus making them difficult to use.